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Koen Kooi
ebbeb55561
Also add script used to generate patches and SRC_URI Signed-off-by: Koen Kooi <koen@dominion.thruhere.net> Signed-off-by: Denys Dmytriyenko <denys@ti.com>
73 lines
2.6 KiB
Diff
73 lines
2.6 KiB
Diff
From 0946969a44d5f9dec1506431e88e942ce924ab82 Mon Sep 17 00:00:00 2001
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From: Jiri Slaby <jslaby@suse.cz>
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Date: Thu, 12 Jan 2012 22:55:15 +0100
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Subject: [PATCH 50/90] TTY: fix UV serial console regression
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commit 0eee50af5b13e00b3fb7a5fe8480419a71b8235d upstream.
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Commit 74c2107759d (serial: Use block_til_ready helper) and its fixup
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3f582b8c110 (serial: fix termios settings in open) introduced a
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regression on UV systems. The serial eventually freezes while being
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used. It's completely unpredictable and sometimes needs a heap of
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traffic to happen first.
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To reproduce this, yast installation was used as it turned out to be
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pretty reliable in reproducing. Especially during installation process
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where one doesn't have an SSH daemon running. And no monitor as the HW
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is completely headless. So this was fun to find. Given the machine
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doesn't boot on vanilla before 2.6.36 final. (And the commits above
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are older.)
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Unless there is some bad race in the code, the hardware seems to be
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pretty broken. Otherwise pure MSR read should not cause such a bug,
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or?
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So to prevent the bug, revert to the old behavior. I.e. read modem
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status only if we really have to -- for non-CLOCAL set serials.
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Non-CLOCAL works on this hardware OK, I tried. See? I don't.
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And document that shit.
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Signed-off-by: Jiri Slaby <jslaby@suse.cz>
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References: https://lkml.org/lkml/2011/12/6/573
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References: https://bugzilla.novell.com/show_bug.cgi?id=718518
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Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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---
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drivers/tty/tty_port.c | 12 +++++++-----
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1 file changed, 7 insertions(+), 5 deletions(-)
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diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c
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index ef9dd62..bf6e238 100644
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--- a/drivers/tty/tty_port.c
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+++ b/drivers/tty/tty_port.c
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@@ -227,7 +227,6 @@ int tty_port_block_til_ready(struct tty_port *port,
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int do_clocal = 0, retval;
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unsigned long flags;
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DEFINE_WAIT(wait);
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- int cd;
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/* block if port is in the process of being closed */
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if (tty_hung_up_p(filp) || port->flags & ASYNC_CLOSING) {
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@@ -284,11 +283,14 @@ int tty_port_block_til_ready(struct tty_port *port,
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retval = -ERESTARTSYS;
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break;
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}
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- /* Probe the carrier. For devices with no carrier detect this
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- will always return true */
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- cd = tty_port_carrier_raised(port);
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+ /*
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+ * Probe the carrier. For devices with no carrier detect
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+ * tty_port_carrier_raised will always return true.
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+ * Never ask drivers if CLOCAL is set, this causes troubles
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+ * on some hardware.
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+ */
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if (!(port->flags & ASYNC_CLOSING) &&
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- (do_clocal || cd))
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+ (do_clocal || tty_port_carrier_raised(port)))
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break;
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if (signal_pending(current)) {
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retval = -ERESTARTSYS;
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--
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1.7.9.4
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